Climbing robots are used for a variety of applications, such as window cleaning, structural inspections, reconnaissance and sensor deployment.
Adhesion and locomotion are two key functions of a climbing robot. Locomotion can be achieved via mechanisms such as wheels, tracks or actuated legs. Numerous adhesion mechanisms exist for holding climbing robots to the surfaces they will move along, including magnetic and electrostatic mechanisms, ducted fans, non-contact Bernoulli type attractors and vacuum adhesion mechanisms.
Based on the means of generating adhesion force to the wall, vacuum adhesion mechanisms can be classified into two main types: active vacuum which requires continuous power to maintain a vacuum and passive vacuum in which power is required to generate or release a vacuum but not to maintain it. The overall energy required maintaining adhesion to the wall, the noise pollution levels, the range of applicable surfaces and the mechanical complexity of each mechanism varies.
For example, the amount of energy required per kilogram of robot weight can be 2 kW/kg adhesion force for a ducted fan, 600 W/kg for a non contact adhesion device, 30 W/kg for a vacuum pump cup configuration.
Active Vacuum Generating Mechanisms
Active vacuums require constant power supply, potentially reducing the operating duration of a climbing robot by draining batteries faster. Active vacuums also require a vacuum pump, adding weight and reducing payload capacity.
Passive Vacuum Generating Mechanisms
U.S. Pat. No. 4,477,998 discloses a wall climbing toy with suction disks mounted on a conveyable belt as the adhesion mechanism. The belt is driven by a motor which allows it to rotate and wires are attached to the suction cups in order to prime and release the suction cups at the initiation and completion of each suction cup's contact with the surface.
WO2011/029206 discloses a suction device for robotic climbing applications which includes at least one flexible suction cup where suction is created by a rod attached at one end to the suction cup and at the other to a vacuum actuator. Movement of the actuator raises the centre of the suction cup thereby creating a vacuum. The pads adhere one, at a time and the device rotates its way up the wall, resulting in slow movement.
Yoshida et al (Design of a wall climbing Robot with Passive Suction Cups, Yoshida et al, IEEE International Conference on Robotics and Biomimetics (ROBIO), 2010) discloses a wall climbing robot.
The design incorporates multiple passive suction cups mounted on the outer surface of a rotating belt and involves an on/off release function, similar to that disclosed in U.S. Pat. No. 4,477,978. Yoshida notes problems with the design such as significant difficulty encountered when moving the robot on the wall.
U.S. Pat. No. 7,775,312 discloses a rolling vacuum seal mechanism and suggests that sliding suction climbing devices have significant faults such as premature and excessive wear on the seal portion and an inability to negotiate surface obstructions without suction loss. The references cited in U.S. Pat. No. 7,775,312 (U.S. Pat. No. 4,926,957, U.S. Pat. No. 5,536,199 and U.S. Pat. No. 5,752,577) all require an active vacuum source such as a vacuum pump or blower.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date.